There are known displays embodied in flat cells. A cell is usually formed by two parallel glass plates, on the inner sides of which are electrodes made from optically transparent conducting materials, and alignment layers. After assembly of the cell, the cell is filled with a liquid crystal material which forms a layer having thickness ranging from 5 to 20 μm. The liquid crystal material is an active medium that changes its optical properties such as angle of rotation of polarization plane under the influence of an electric field. Variations of optical properties are viewed in the crossed polarizers, which are usually glued on the external surfaces of the cell. The areas of the display where electrodes are not electrically charged transmit light and look bright, while the areas under voltage look dark (L. K. Vistin. JVHO, 1983, vol. XXVII, ed. 2, pp. 141-148).
In reflecting displays, a mirror or reflector is provided behind the LC cell so that the incident light passes through the cell twice. Formation of an image is performed analogously to the transmission displays (Pochi Yeh, Claire Gu, Optics of Liquid Crystal Displays, N.- Y., 1999, pp. 233-237).
The main drawback of traditional displays is the small viewing angle since only the light flow propagating towards the front surface of the multilayer LC display within the limits of a confined cone angle efficiently governs the multilayer design of the LC display. Such displays usually use absorbing polarizers based on a polymer such as polyvinyl alcohol having optical anisotropy, which can be obtained via monoaxial stretching of the film of this polymer as described in U.S. Pat. No. 5,007,942, and subsequent dyeing of the film in iodine fumes or in an organic dye. Thus the ellipsoids of angular dependence of the real and imaginary parts of refraction index of the polarizer have stretched-out (needle-like) shape.
The traditional displays also have relatively low brightness, low contrast and high power consumption due to the large number of absorbing layers.
Color displays usually have the same design wherein color filters are used. Each pixel of a color image is formed via mixing of three colors (red, blue and green) in a proper ratio (Nikkei Electronics, 1983,5-23, p.p. 102-103). Using absorbing filters may cause additional light losses in the device and as a consequence increase energy consumption.
There are known LC displays where the polarizer layer is obtained from aligned supramolecular complexes of a dichroic dye. Such polarizers have high optical characteristics and small thickness, which allows their placement inside the display. This simplifies the design and increases durability of the display. In addition, the fabrication technology of such layers allows combining several functions in a single layer (for example the function of polarizer and LC alignment layer) (RU 2120651, 15.04.96).
WO 99/31535 describes a liquid crystal display which incorporates a polarizer containing a birefringent anisotropically absorbing layer having a refraction index that increases with the increase of the wavelength of incident light. In particular, such polarizer may be obtained from LLC dichroic dye and may have certain thickness to establish interference extremum on at least one side of the polarizer. The above noted patent application also describes a reflecting polarizer.
One of the drawbacks of using such polarizers for color display is that they reflect light in a wide spectral range which leads to smeared colors. In addition, further development of display technology requires better optical characteristics of polarizing elements, particularly increased viewing angle at which there is an efficient light transformation.